Question

Вчера в классе присутствующих было в 8 раз больше, чем отсутствующих. Сегодня не пришло еще 2 ученика, теперь отсутствующие составляют 20% от присутствующих. Сколько всего учеников в классе?

Answer 1

20%-0,2

Пусть Х - число отсутствующих вчера учеников, тогда число присутствующих вчера 8х. Всего учеников  в классе х+8х=9х. Сегодня присутствовало (8х-2) учеников, а отсутствовало (х+2) или 0,2(8х-2). Составим и решим уравнение:

0,2(8х-2)=х+2

1,6х-0,4=х+2

1,6х-х=2+0,4

0,6х=2,4

х=2,4:0,6

х=4

9*4=36

Ответ: всего в классе 36 учеников.

Answer 2

Problem Analysis

To solve this problem, we need to determine the total number of students in the class. We are given two pieces of information: 1. Yesterday, the number of present students was 8 times greater than the number of absent students. 2. Today, two more students are absent, and the absent students now make up 20% of the present students.

Let's break down the problem and solve it step by step.

Step 1: Yesterday's Information

According to the first piece of information, yesterday the number of present students was 8 times greater than the number of absent students. Let's assume the number of absent students yesterday was x. Therefore, the number of present students yesterday would be 8x.

Step 2: Today's Information

According to the second piece of information, two more students are absent today, and the absent students now make up 20% of the present students. Let's assume the number of present students today is y. Therefore, the number of absent students today would be 0.2y.

Step 3: Combining the Information

We can now combine the information from yesterday and today to form an equation. The total number of students in the class is the sum of present and absent students. Therefore:

8x + x + 0.2y + 2 = y

Simplifying the equation:

9x + 0.2y + 2 = y

Step 4: Solving the Equation

To solve the equation, we need to isolate the variable y. Let's move all the terms with y to one side of the equation:

0.2y - y = -9x - 2

Simplifying further:

-0.8y = -9x - 2

Now, let's divide both sides of the equation by -0.8 to solve for y:

y = (-9x - 2) / -0.8

Step 5: Finding the Total Number of Students

To find the total number of students in the class, we need to substitute the value of y into the equation:

Total number of students = 8x + x + 0.2y + 2

Substituting the value of y:

Total number of students = 8x + x + 0.2((-9x - 2) / -0.8) + 2

Simplifying the equation:

Total number of students = 8x + x - 0.25(-9x - 2) + 2

Now, we can solve this equation to find the total number of students.

Solution

To find the total number of students in the class, we need to solve the equation:

Total number of students = 8x + x - 0.25(-9x - 2) + 2

Unfortunately, we don't have enough information to determine the exact values of x and y or the total number of students in the class. We would need additional information or equations to solve the problem.

If you have any additional information or equations, please provide them, and I'll be happy to help you further.